Both are great.
It depends on the usage... and how you are set up to handle leaf work / debris / clippings....
Are you able to dump from the seat onto the ground? like in the woods or curbside for pickup?
Or do you need to dump the clippings into the back of your truck?
The dump from the seat Bac-Vac is the quickest and easiest for sure, but the 3 bag will enable you to take the bags off and dump them in the truck.